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CMMRS > Chapter 11: Haemophilus, Bordetella, and Legionella > Flashcards

Chapter 11: Haemophilus, Bordetella, and Legionella Flashcards

1
Q

Haemophilus infleunzae

A 
Requires blood-containing medium for growth
Needs Hematin and NAD+ from blood 
Obligate human parasite 
Transmission: respiratory 
Gram-neg rods
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2
Q

What confers virulence in Haemophilus influenzae?

A

Polysaccharide capsule

  • composed of polyribitol ribose phosphate
  • 6 types of capsules: B is invasive disease in children (meningitis, epiglottis, and septic arthritis)
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3
Q

Is Haemophilus influenzae the etiologic agent of the flu?

A

No, the bacterium often attacks the lungs of persons debilitated by a VIRAL influenza infection

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4
Q

Nonencapsulated/nontypeable Haemophilus infleunzae

A

Can colonize the URT of children and adults
Lack virulent invasiveness: only cause LOCAL infection
Freq cause otitis media in children
Respiratory disease in adults with preexisting lung disease

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5
Q

Who gets frequent infections iwth nontypeable H. Influenzae?

A

Pts with COPD

Causes COPD exacerbation

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6
Q

Haemophilus influenzae type b causes what diseases?

A

Meningitis, Acute epiglottitis, Septic arthritis, Sepsis

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7
Q

What is the most serious infection caused by encapsulated Haemophilus influenzae type b?

A

Meningitis

Main cause of meningitis in young children btwn 6 mts to 3 years (before vaccine)

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8
Q

How does Haemophilus influenzae type b cause meningitis?

A

Inhalation: invades local LNs and blood-stream
Penetrates into the meninges

When destroyed with antibiotics, lysed bacteria releases LPS lipid A causing violent immune response that destroys neurons

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9
Q

What are the signs of meningits in infants with Haemophilus influenzae type b infection?

A

Usually do not display classic stiff neck

Non-specific signs: fever, vomiting, altered mental status

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10
Q

Acute epiglottitis

A 
Children
Rapid swelling of the epiglottis, obstructing respiratory tract and esophagus 
Follows sore throat and fever 
Stridor/wheezing 
Unable to swallow 
Drool 
Cherry red epiglottis 
DO NOT examine larynx ->laryngeal spasm->complete airway obstruction 
H. Influenzae type b
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11
Q

Septic arthritis by Haemophilus influenzae type b

A

MOST COMMON CAUSE of septic arthritis in infants
Single joint
Fever, pain, swelling, decreased mobility of joint
Pleomorphic gram - rods in synovial fluid

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12
Q

Sepsis and Haemophilus influenzae type b

A

Children 6 mts - 3 yrs
Fever, lethargy, loss of appetite, no localized disease
Invade blood-stream via URT
Absent spleen or non-functioning spleens cant fight off infection: highest risk

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13
Q

What is Haemophilus ducreyi responsible for?

A

Sexually transmitted disease chancroid
Painful genital ulcer
Unilateral painful swollen inguinal LN rapidly develop
LN become matted and rupture - releasing pus
NO systemic symptoms
Ulcer and Swollen LN coexist

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14
Q

What can Chancroid commonly be confused with? Differential diagnosis?

A

Syphilis: ulcer painless, LN bilateral and painless, no pus
Herpes (simplex 1/2): Blisters, when burst can look like chancroid, painful. Systemic: fever, myalgias
Lymphogranulom venereum:Chlamydia trach, Painles matted, pus inguinal LN. Primary ulcer disappears before nodes enlarge

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15
Q

H. Ducreyi

A

Gran-negative cocobacilli

No exotoxins

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16
Q

HACEK

A 
Slow growing bacteria that cause endocarditis
Haemophilus
Actinobacillus
Cardiobacterium 
Eikenella 
Kingella
17
Q

Cardnerella vaginalis causes what?

What are the clue cells ?

A

Causes bacterial vaginitis in conjuction with anaerobic vaginal bacteria
S/S: Burning or itching of labia, buring on urination (dysuria), fishy odor

Clue cells: vaginal epithelial cells that contain tiny pleomorphic bacilli within cytoplasm

18
Q

Bordetella pertussis causes what?

A

Whooping cough

19
Q

Describe Bordetella pertussis

A 
Gram - rod
4 major virulence factors:
- Pertussis toxin
- Extra cytoplasmic adenylate cyclase
- Filamentous hemagglutinin
- Tracheal cytotoxin
20
Q

Pertussis toxin

A

B subunit
A subunit: activates G reg proteins -> Adenylate cyclase

Exact role?

  1. histamine sensitization
  2. Increase in insulin synthesis
  3. Promotion of lymphocyte production and inhibition of phagocytosis
21
Q

Extra cytoplasmic adenylate cyclase

A

Swallowed by host neutrophils, lymphocytes, and monocytes
Internalized AC synthesized cAMP
Results in impaired chemotaxis and impaired generation H2O2 and superoxide
Weakens phagocytosis

22
Q

Filamentous hemagglutinin (FHA)

A

Pili rod extending from Bordetella pertussis surface. Helps bind to ciliated epithelial cells of bronchi (Bordetella doesnt invade)

23
Q

Tracheal cytotoxin

A

Destroys the ciliated epithelial cells
Results in impaired clearance of bacteria, mucus, and inflammatory exudate
Possibly responsible for violent cough

24
Q

Whopping cough

A

Mostly adolescents and aduts
Highly contagious disease
A week-long incubation period
Increase in Lymphocyte count not neutrophils
3 stages of disease: catarrhal stage, paroxysmal stage, and convalescent stage

25
Q

Catarrhal stage of whooping cough

A

1-2 weeks
Similar to URTI
Low grade fever, runny nose, sneezing and mild cough
MOST contagious

26
Q

Paroxysmal stage of whooping cough

A

Fever subsides
Nonproductive cough bursts
15-25 attacks per day (appear normal btwn events)
During episodes: pts becomes hypoxemic and cyanotic, tongue protrude, eyes bulge, neck veins engorge, vomit
Lasts a month or longer
More severe in young (cough and apnea spells)

27
Q

Convalescent stage of Whooping cough

A

Attacks become less frequent over a month

No longer contagious

28
Q

How to test of whooping cough

A

Organism will not grow on cotton
Use Ca alginate swab
Culture on medium with potato, blood and glycerol agar = Bordet-Gengou medium

29
Q

Legionella pneumophila

A

Aerobic gram-negative rod
Sources: air conditioning systems, cooling towers, whirlpools
Facultative intracellular parasite (for amoebas)
Settles in lower respiratory tract
Cal enter low metabolic state and survive in biofilm

30
Q

What diseases is Legionella responsible for?

A

Pontiac fever

Legionnaires’ disease

31
Q

Pontiac fever

A

Headache, muscle aches, fatigue, followed by fever and chills
Strikes suddenly and completely resolves in less than a week
Legionella pneumophila

32
Q

Legionnaires’ disease

A

Common cause of CAP
Causes classic lobar consolidative pneumonia similar to pneumococcal pneumonia
Unusual: fever with pulse-temp dissociation (high fever/low HR), sever headache, confusion, myalgia
sometimes rhabdomyolysis (muscle breakdown with increased lvls of serum CPK and myoglobinuria)
Cough, hyponatremia, hypophosphatemia and AST, ALT increase

CMMRS (27 decks)

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